Posted
by
timothy
on Sunday September 11, 2011 @01:10AM
from the plus-they're-near-deal-extreme-for-lasers dept.

First time accepted submitter ToBeDecided writes "A U.S. military reconnaissance plane was reportedly forced to perform an emergency landing during a major military exercise near the North Korean border in March. As revealed by the South Korean defense ministry, a strong signal transmitted from the north disrupted GPS in the area surrounding the position of the RC-7B aircraft. Without information about their position, the pilots were forced to abort their mission and return to South Korea. This raises the question whether the U.S. military would be able to perform operations in North Korea given how fragile their equipment seems to be."

That eventuality is presumed within the question of "whether the US military would be able to perform operations in North Korea". The question being asked is whether or not, should the need arise, the US military would be able to function in or near North Korea given the situation described above. The "need arising" means war. So, yes, presumably in peactime North Korea is able to disrupt the navigation systems of US recon planes in the area, and removing that capability would be an act of war.

Should hostilities start, presumably those capabilities would be disabled (or at least such disabling would be attempted) and whether or not that would be an act of war would be a moot question-- else why is there a need for the US to "conduct operations" in North Korea?

I agree. ALL aircraft have on-board inertial navigation systems as well. And when all else fails, a map and a compass works just fine too. I smell BS.

Agreed, plus this seems like a pretty dumb thing to do if they were ever planning a war, to show us all their new toys since now we know what they're capable of and can figure out a strategy. It's like they're showing us their cards, wouldn't a powerful GPS jammer be something they'd want to keep hidden? Pull out the GPS jammer when the GPS-guided tomahawk missiles [wikipedia.org] are on their way, not when a reconnaissance plane is doing a annual drill. [wikipedia.org]

I think it went like this:
Pilot: Command we're experiencing problems with GPS, some sort of interference
Command: Can you identify the source?
Pilot: Seems to be originating from NK
Command: Is it effecting your ability to fly?
Pilot: Negative
Command: Continue operations as scheduled and chart locations of interference so we can pinpoint jammer locations.
Pilot: Roger
Command: (We were only doing a yearly drill but NK gave us the exact location of their GPS jammers! NK you are very stupid)

From what I have read, NK seems to be in a state where you get status/promotion by doing slightly provocative things so you become visible to your superiors. The resulting behavior is somewhat like what you see elementary school boys but much more serious. (I do not mean to imply that they are intellectually children, but the competition is so tight)

It is said to be true only when there are power struggles in progress. If you cross the line too far, you wind up dead.

China does what is best for China. Getting into a hot war with the US will result in both the US, and the countries aligned with the US, ceasing to buy everything that China is selling. Collapsing China's enconomy is not what's best for China. Therefore China will not directly interfere with a war in North Korea unless, as in the first round, it looks like China herself is actually going to be invaded.

If China waited until it looked like MacArthur wasn't going to stop before rolling over the border the firs

South Korea (and its allies, like the US and Japan) and North Korea are technically still at war with each other and people do occasionally get killed. So a lot of "acts of war" happen rather frequently. A more nuanced view IMHO is that this would be an unnecessary and risky escalation of a minor hostility.

by the Webster definition of sabotage - it fits. Although it was hard from being "passively" interfered with, GPS antennas on most military aircraft are designed to be resistant to jamming (usually through spatial diversity) however if a sufficiently strong signal is directed at you it all comes down to physics and can the GPS receiver recover the small satellite signals out of the noise. I wouldn't be surprised if the aircraft in question was being tracked with a ground based radar and the GPS jammer wa

Almost all of the time. The US has by far the world's most powerful military, and has for over a half century. For over a century before that the US military was among the top 5, though probably actually still the most powerful since about the 1860s, but confined to North America. During that time the US has invaded only its neighbors to the west (native nations) and south (Spanish Mexico, and then Mexican Mexico), and not for a century now, and very occasionally small distant countries with either no substantial military (Grenada), or similarly sized military (Iraq, Nazi Germany), or substantial counter-insurgency communities (Vietnam, Afghanistan).

Yes, the US is at war (overt or covert) almost all of the time. But there have always been far more opportunities for the US to make war with its huge military and bloodthirsty population than it has exploited. During most of its history other nations with big militaries have made more war.

So while most of US history has featured acts of war by the US, that's just a small percentage of the time the US could have committed acts of war. Most of the time something's stopping us, because we aren't doing nearly as much as we could.

Inertial guidance is nothing new, it was developed in the 1930s, German V1 and V2 missiles used it.

Two problems: it's less accurate and much more expensive than GPS. If you want military superiority you need both, Inertial guidance is for situations where GPS is jammed.

There are several other types of guidance systems, the US military has them all. One wonders about the wisdom of so much research on weapon systems, but it's a fact that it provides useful side-effects on civilian systems.

And then after your country is bombed into the stone age anyway you will be prosecuted for war crimes.

Not necessarily. Haven't the fighters in the Gaza Strip successfully shot rockets from schools and other such places, and caused Israel to get all kinds of worldwide criticism when they fired upon those locations? I haven't heard of anyone in Hamas being prosecuted for war crimes.

While that is perfectly true - the question remains. Why is an aircraft unable to perform it's mission because GPS has been knocked out? A pair of well trained pilots in a recon craft should be able to navigate with, or without GPS. There should be redundant systems aboard the craft, and if all the navigation systems fail and/or become questionable, the pilots themselves should be able to navigate.

Our reliance on high tech may well be our undoing. Remember, some dumb grunt with a sharp stick can make yo

Which doesn't negate his point. What could be considered a minor operational risk in active combat would be considered a much more serious risk in a training exercise. While we're technically at war with North Korea, there are no active hostilities and violating the border would still be considered a serious incident (much more so than passive GPS interference). There is also a small but not insignificant increased risk to flying the plane without all systems go. A commander in an exercise is more likel

Why is an aircraft unable to perform it's mission because GPS has been knocked out

Because it has to stay on the south side of the border. If it strays over the DMZ then it becomes a legitimate target. If it's then shot down, then it's a diplomatic and political nightmare for the USA - they can't do nothing without looking weak, and they can't retaliate without escalating the conflict.

In a combat scenario, this is irrelevant. It would just fly over the border and take pictures. The inertial guidance system is more than accurate enough for this kind of activity.

Should be fairly simple to move a few kilometers to the south until the interference clears up. I don't expect a pilot to fly with a 300m accuracy over a nearly invisible jagged line by sight, but a few kilometers should be child's play.

But then they'd probably be out of the area designated for the exercise. And, as another poster pointed out, it's common to abort exercises because of equipment failure, rather than keep using the failed equipment and make it harder to diagnose the fault. Part of the point of exercises is to check that everything is reliable. When you find something that isn't, you stop and fix it. In a war situation, you'd just switch to the backup system (INS in this case).

They can probably do it, but they risk starting a huge incident if they happen to make an error and stray into the wrong airspace... safer to just go home. I would suspect this is a safety consideration more than a "oh no, our equipment is useless" situation.

Perhaps their mission involved pinpointing items of interest. This might be performed through a combination of range/bearing from current location, and that current location. If you want accuracy GPS is likely the way to go.

I'm TOTALLY speculating here, I've no idea what they were up to or the tech. they'd have been using.

This raises the question whether the U.S. military would be able to perform operations in North Korea given how fragile their equipment seems to be."

This says nothing about fragile equipment, this is about a jammer putting out a signal stronger than what is coming from the satellites above. The signal from the satellites is well known, and thus figuring out how to jam it is just a matter of signal strength and what type of jamming they want to do. Do they want to just bury the signal in noise, or are they trying to send false data to lure US and ROK units into NK air and sea space?

Do they want to just bury the signal in noise, or are they trying to send false data to lure US and ROK units into NK air and sea space?

Explain why it has to be binary. If I were running the op in N.K., I'd have a modest yet respectable and noticeable jammer doing mission #1, and a whopping boom-car monster of a jammer doing mission #2. So, they steer out of range of mission #1, trust their instruments, and therefore fly into the side of a mountain because of mission #2. Insert N.K. version of simpsons "ha ha" voice. Don't get all moralistic as if we wouldn't do the same to a nation that had air superiority over us...

We should all also agree that in contrast, if a vessel is taken out by simply disturbing GPS signals, that it's as fragile as a paper plane.

Not really. The plane did not crash.It returned safely. To me that means it was able to fly.

To be sure that it was as vulnerable as a paper plane, we must also be sure that in peace time and in ware time, the same precautions are taken. For all I know during a war time mission, they would say 'Turn of the GPS and use other things to get where we drop our bombs'. While n

"We should all also agree that most vessels even have some protection for such violent attacks."

Actually, no. There are very few aircraft that are armored. Some aircraft have a few "hardened" points within the craft, ie, the cockpit on commercial craft have locking hatches nowadays. Armoring an aircraft just enough to protect against a near miss from a fragmenting missile is prohibitively expensive, in terms of fuel and maneuverability, not to mention the cost of the aircraft.

I'm sure that they had inertial navigation as you described. Probably that would be enough for most situations and they simply made a decision to return in order to be sure not to get into needless trouble. However, this was a spy plane; it should have pretty much top end GPS equipment and it is high up. In that situation, it should be easy to use a directionally selective GPS antenna which ignores Satellites in the direction of the jamming signal (e.g. below the horizon). It's a pretty major problem if

It's believable that the GPS system got disrupted, but it's hard to believe that this somehow forced them to land. If they were doing recon, then GPS is pretty critical so that they can exactly pinpoint what they're surveying. However, even the lowliest pilots can navigate without GPS (this is required to pass any level of flight school, let alone military-level). I can understand the mission being scrapped due to this type of disruption, but I can't believe that they were in any sort of danger.

the headline makes it seem like north korean jets surrounded the recon plane and gestured it to land "or else", because that's what a forced landing is.the headline sounds like fucking north korean loyalists wrote it.

in other news north korea "forced" the entire air fleet involved in the operation to eventually return to base!

The more interesting story here is that the US is doing exercises near North Korean airspace. Here is a militaristic country with nuclear weapons and with China on one side and South Korea on the other, as well as Japan close by. They have medium range ballistic missiles and nuclear weapons. Everyone wants them to stop antagonising their neighbours, launching missile tests over them, doing nuclear testing... And the US and Japan have perfectly good spy satellites.

The more interesting story here is that the US is doing exercises near North Korean airspace. Here is a militaristic country with nuclear weapons and with China on one side and South Korea on the other, as well as Japan close by. They have medium range ballistic missiles and nuclear weapons. Everyone wants them to stop antagonising their neighbours, launching missile tests over them, doing nuclear testing... And the US and Japan have perfectly good spy satellites.

Operation Team Spirit has been going on in Korea for DECADES.

There were a bunch of years in the late 80's and early 90's where NK would offer to come to talks if OTS was called off. So they'd opt out of OTS for a year and then NK would send us a "Fuck you capitalist pigs!" message.

Finally, back in 1992 they basically chose to ignore NK and carried on with OTS again.

"This raises the question whether the U.S. military would be able to perform operations in North Korea given how fragile their equipment seems to be."

What an amazingly stupid statement. All kinds of things to consider:

1) Rules are different for peace time and war time. You are more careful in an exercise than in combat. Planes have other navigation systems, like inertial navigation, however they aren't as precise. During a drill, you take the careful approach, abort, and back out. In combat, probably not.

2) The reason precise positioning is so important in this case is because they need to make sure to not cross the border. This matters less in wartime. There are things that call for precise positioning but not ever flight needs it all the time.

3) They managed to get one plane to land. Oh wow, that would be useful if the US had 2 planes but they don't, they have thousands. Does the system work so well against that many?

4) Anything generating a signal is a target. Lock on the signal and blast it. There are even missiles for that sort of thing called AGM-88 HARMs. Their design is to nail radar facilities but it wouldn't take much change to make them nail GPS jammers, and the US may already have models for that.

5) How well is this going to work if you don't know the planes are even there, like say the B-2Bs, which they can't detect to target, and yet which can carry tons (literally) of precision munitions?

While I'm sure the US isn't pleased about this and it doesn't help, it isn't as though this would suddenly stop US craft from functioning. All it can do is stop precise navigation in whatever area it is effective in. It also can only do so as long as it can transmit. Anything hostile that broadcasts a signal had better be able to move fast and defend itself. If not, it will go 'asplode in a big hurry.

I've got a friend who lived in Yugoslavia when NATO attacked. NATO had these anti radar missiles, tens of thousands of dollars a pop. The Yugoslavs took old microwave ovens out into the field, rigged them to work without a door and pointed them at the sky. they would flick them on when NATO planes were reported. The plane would empty it's load of anti radar missiles and immediately turn home.

First because of all the claims "I've got a friend who..." has to be the least reliable form of evidence ever. Sorry, but the amount of made up shit out there is legendary, and gets worse in each retelling. It isn't just a story, it is hearsay of a story.

Then there's the fact that military radars don't work at 2.4GHz. If the S band was in heavy use for that, there would be problems with interference with other 2.4GHz devices. Military radar is mostly X band (8-12GHz). If you think that these things can't be designed to sniff for different ranges, you are kidding yourself.

Then there's signal strength. A microwave's magnetron is 1000 watts or so, and is not designed for directional transmission. Military radar is an order of magnitude above that or more. It is also steered directionally towards what you want (either mechanically or by phased arrays) to keep power dispersion down. A microwave would not show up at all the same as a military radar.

Finally there's the fact that, well, it clearly didn't do much even if it happened. Yugoslavia lost, rather badly, to nothing but an air war. They left Kosovo. It wasn't as though the NATO planes were befuddled and they had to send in ground troops. It was the first war where airpower alone did the trick.

Back on topic, that kind of thing would do jack and shit for the North Koreans with regards to GPS jamming. Not only does the signal need to be much more powerful, but it is the wrong band. GPS works in the L band. Building high power, L band decoys might work... But then those are probably effective jammers so no real difference.

GP's anecdote seems to be a folk exaggeration of the story of Zoltan Dani [wikipedia.org], the "I've shot down an F-117" Serbian guy. Quoting Wikipedia:

Lt. Col. Dani made it a strict field rule that the SA-3's UNV type fire control radar could only be turned on for a maximum of 2 x 20 seconds in combat, after which the battery's equipment must be immediately broken down and trucked to a pre-prepared alternative launch site, whether or not any missile has been fired. This rule proved essential, because other Serbian AAA units, emitting high-frequency radiation for any longer periods or forgetting to relocate, were hit by AGM-88 HARM missile counter-strikes from NATO aircraft, suffering radar equipment and personnel losses.

Radar sets obtained from confiscated Iraqi MiG-21 planes were planted around the SAM sites to serve as active emitter decoys, which diverted some anti-radiation missiles from the actual targets (dozens of Iraqi MiG-21/23 warplanes, sent to Yugoslavia for industrial overhaul, were seized in 1991, after Saddam Hussein's invasion of Kuwait.) Retired SAM radar sets were used as optical decoys, left at well-known military bases to lure NATO planes waste munition on worthless targets. Owing to these measures, Dani's unit evaded 23 incoming HARM missiles, all of which impacted off-site with insignificant or zero damages.

This was probably overlaid on top of other factual stories of Serbs using decoys for their military equipment to curtail damage. Also from WP:

Most of the targets hit in Kosovo were decoys, such as tanks made out of plastic sheets with telegraph poles for gun barrels, or old World War II–era tanks which were not functional... At the end of war, NATO officially claimed they destroyed 93 Yugoslav tanks. Yugoslavia admitted a total of 13 destroyed tanks. The latter figure was verified by European inspectors when Yugoslavia rejoined the Dayton accords, by noting the difference between the number of tanks then and at the last inspection in 1995.

Similar figures are there for other equipment. So Yugoslavia did not suffer significant military damage or casualties - most of NATO bombings disrupted civilian infrastructure (which NATO has conveniently redesignated as "dual-purpose", leading to events such as Grdelica train bombing), and most victims of them were civilians. But the way Serbia avoided decimation of its military was, effectively, by dodging the open fight.

Shame on the RIO for not being able to distinguish between a dirty, non-directional S-band emitter, and a C or X band sweeping search radar. The only constant signal would be targeting radar, which would be a much higher effective power, and much higher frequency, than that microwave.

The U.S. military now have better knowledge of the North Korea's capability and tactics. They now know that in the even of war, before the drop any GPS guided munitions, they now have the exact location of a target to take out.

This is no different to the old Soviet days, when US planes would test Soviet defenses, provoking a reaction to gain intelligence.

On the other hand, knowing that they have this capability and what it looks like to our aircraft, and perhaps where it came from - these things might be very valuable intel indeed. So, maybe we really *are* pleased...

Or maybe the U.S. *wants* North Korea to think that the U.S. is not pleased.

Although... North Korea showing their hand by jamming a signal in peace time is a pretty stupid move. Maybe North Korea *wants* the U.S. to think that North Korea is pleased about jamming a U.S. plane, when infact they have a much more powerful jammer which they didn't use. Hmm....

This raises the question of 'How did they do this in World War II, before we had GPS?'

Very badly. Aerial navigation in WWII barely worked.
Bombers routinely had trouble finding their targets. The V-1 and V-2 could at best hit a city-sized target; using them to attack an airfield was hopeless. (Had they been accurate enough to hit airfields, the Battle of Britain might have turned out differently.) There were various radio beam schemes, most of which were jammable.

Much bombing was done by sending in the best navigators as "pathfinders". They dropped incendiaries, and the other bombers dropped bombs on the resulting fire. Both sides occasionally set up big bonfires to divert bombers looking for such fires.

Battle of Britain decided by V-2s? Whuh? +5 Informative? In addition to the fact that the V rockets didn't exist in the same timeframe as the Battle of Britain, the Luftwaffe had no problem finding and bombing British airfields. It was a command decision to switch from a war of attrition against British air to terror bombing against cities that allowed the RAF a much-needed breather, at the cost of thousands of civilian lives.

The Pathfinder bombers were purely on the Allied side, in Europe no less. W

Germans lost the Battle of Britain because Hitler forgot the first rule of an air war is to defeat the other guys planes... he switched targets from the airfields to bombing London and gave the RAF a let off... had he kept on bombing the airfields, the RAF would have run out of places to fly from close to the channel and would have been taking off from much further away and thus been on the back foot when it came to actual time to fight in the air... He'd have had local air superiority and then would have b

The V-1 and V-2 could at best hit a city-sized target; using them to attack an airfield was hopeless. (Had they been accurate enough to hit airfields, the Battle of Britain might have turned out differently.)

Battle of Britain - 1940. V1/V2 - 1944/45. Most weapons are ineffective if they come along 4 years too late.

In 1940, the Germans had a weapon that was accurate enough to hit even tanks, much less airfields, the Stuka dive bomber. The trouble is, dive bombers are very vulnerable to fighter opposition unless you have air supremacy, which was what the Germans were trying to achieve in Britain. The Stukas suffered heavily from the RAF and were rapidly withdrawn from the Battle of Britain, which indeed hampered the German ability to take out those airfields.

After the V2 campaign started Germans installed a post-launch radio navigation system which improved the V2 accuracy to a few 100 meters or better. Thanks to the ULTRA / Enigma decrypts, the Brits knew that they were testing this against English targets, were worried about the improved accuracy, and instituted a deception campaign to convince the Germans that they were not actually hitting what they were aiming at. It worked, and they never really made good operational use of the more accurate aiming capabilities.

The U.S. Army is the most powerful fighting force in the history of the world. An M1A2 tank is not fragile. The U.S.S. Enterprise in not fragile. The U.S. Marine Corps is anything but fragile.

Every time U.S. forces have come up against Soviet-doctrine troops and equipment in a regular battle (as opposed to a counterinsurgency campaign) after the Korean War ( a draw), the U.S. has soundly kicked their asses. The more technologically advanced the equipment, the less likely it has been to break down. "Smart" w

There are a bunch of "fragility" issues with some of U.S. military equipment - the whole clusterfuck that is M16/M4 comes to mind - but reliability of equipment is not a sole factor winning the war. U.S. has logistical capabilities superior to pretty much everyone else out there, so things breaking down in the field is less of an issue; and, of course, in any case training is far more important, and U.S. military is also very advanced in that department. Another aspect is that even if some equipment is frag

This left me scratching my head, actually. After Korea, what conflicts were those where U.S. forces have came into open confrontation with Soviet-doctrine troops? Vietnam was, arguably, closer to a "counterinsurgency campaign", really. Do you mean Iraq? these guys were so outclassed hardware it's not even funny, so I don't think it's a meaningful comparison.

I believe the OP is referring to the wars-by-proxy of the Cold War era, where the Soviets would arm one side, the US would arm the other. The Yom Kip

These aren't jet jockeys, these are the "guys in the van". Had they tried being heroic, they'd have probably crashed or been shot down over NK and then they'd have created a huge publicity stunt for North Korea to use in their own favor. There's no reason to give NK free hostages just because the GPS radio didn't work correctly.

Jamming GPS doesn't make them bulletproof. Lack of GPS was a matter of the standing orders being to abort in the event of GPS failure, not even a matter of the navigator being able to use/trust their inertial systems alone.

In a peacetime exercise, the most important thing other than not crashing is to not violate an unfriendly nation's airspace. You need to be quite certain of your exact position. If navigation is less than perfect, it's just not worth the risk.

In a wartime mission, violating the unfriendly country's airspace is implicit. You need navigation good enough to make a sighting of your target.

I'm inclined to believe there's more to it than what's in the story. Military aircraft do not rely solely on GPS for guidance. Perhaps drones and missiles do, but piloted military aircraft have redundant systems for guidance, including a sextant. Why do you think all aircraft other than a few fighters have a pilot and copilot? The copilot can act as navigator, and most tactical aircraft also have a navigator in addition to the two pilots.

Of course, this being just a drill, they may have said "screw it" and just landed. Any real reconnaissance mission would have be continued using redundant systems.

Or, they may have wanted to give that dike looking Kim Jong-il a big head and make him think he made a state of the art US military aircraft run for the boarder.

Any way you look at it, unless he zapped the plane with an EMF pulse strong enough to knock out the avionics systems, there is no way he could have done anything electronically to make them have to perform an emergency landing.

Ditto for the military naval vessels. The civilian naval vessels, yeah, it's possible they don't have anything other than GPS.

US Military pilots have other means of navigation than GPS. During times of actual conflict, these systems are used in order to prevent just these sorts of situations.

During peacetime, though, there's the possibility that the military's use of these resources could interfere with civilian flights--so unless there's an actual war going on in the area, they'll stick with the peacetime stuff.

That's not to say that these other methods are jam-proof--but anyone attempting to jam them will have to work hard enough to make themselves a target for an anti-radiation missile.

This is all coming from one story from Agence France-Presse. More info is needed. The US DoD says they don't have a record of this happening.

It's possible that it might be a South Korean plane of a US type, not a USAF plane. If someone was just up on a routine training flight, they might choose to land due to a GPS failure. With no mission to complete, there's no reason not to. Wait for Aviation Leak to cover the story.

All major USAF aircraft have inertial navigation capability, and have for decades. Everyone assumes GPS will be jammed. Even "smart bombs" have a low end inertial navigation system, one that gets its initial fix from the much better INS in the aircraft and only has to guide for about a minute.

Maybe the crew was playing with an RC car on board the aircraft and that jammed the signals. Obviously too embarrassed to confess such an act, the crew hastily created some excuse about North Korean jamming equipment.

The US is denying this happened, and I'm inclined to believe them. Pilots have to learn to navigate without instruments, including gps. Jamming a gps system wouldn't force anyone to land.
Also, this gps jamming signal is a giant target. In an actual conflict it would be a giant sign saying "DROP BOMBS ON ME".

More than IAS was lost. I understood the gyro was tumbled. And look at the way the stall warning was configured. It periodically went on and off gain as it "decided" IAS was reliable or not reliable. Also your IAS was coming online and back offline. I am as suspect of the crew as anybody is, but the situation they were faced with was pretty much the worst imaginable.

The Navy, at least, was working on an automatic "sextant" (i.e., an autonomous optical navigator), precisely so that they wouldn't have to teach celestial navigation any more. I don't know if they have actually made that change.

Why should the plane demonstrate whether it has ability to navigate under a certain type of jamming? I lived close to the inner-german border at cold war times and i saw the funny patterns which were flown, obviously to test the enemy radar capabilities and confuse them.

The article mentions that the jamming signal came from two North Korean cities so I wonder if GPS is routinely jammed in North Korea and if the jamming signal was accidentally on purpose leaked across the border.

I do wonder if the reason they aborted was simply because it was the easier thing to do. If North Korea are being dicks, it's far easier and less risky to just let them get on with it - so long as they're not doing anything more than just being a PITA.

I'm sure the crew of an RC-7B is actually more than capable of navigating without GPS, if they needed to. Pilots managed it for decades before GPS was invented. Sailors managed it for millennia.

This raises the question whether the U.S. military would be able to perform operations in North Korea given how fragile their equipment seems to be."

Let's assume that the incident really did happen. The US has already denied it, but less assume it happened. Jamming is all about blasting a very loud signal that drowns out other signals. During a military operation GPS jamming the US is a pretty ineffective technique for a number of reasons.

First, there are a number of methods of navigating and targeting without GPS. GPS is easy and accurate, but if all of the GPS satellites fell out of the sky, they US military would still happily navigate its planes around and drop bombs. The US military is designed to go toe to toe with Russia and China. Go ahead and assume that the idea that their GPS satellites might be denied to them has crossed their minds. The US doesn't build stealth bombers to kill sheep herders. The US military might be good and killing sheep herders, but it is designed to fight a modern military.

Second, if you are dumb enough to turn on a GPS jammer powerful enough to knock out a plane's GPS navigation during a time of conflict, you pretty much deserve the missile that is going to fly up your arse a few minutes later. Jamming is done by blasting a very powerful signal out into the air. A very powerful signal is trivial to track. You might as well paint your GPS jamming equipment bright red and leave it out in an open field with arrows pointing to it. The first thing the US does in any sort of air war is to level anything that transmits. Normally, this is for taking out radar stations to blind air defenses, but it also applies to any attempts to jam. You really don't want to try and get into an ECM battle with the US. If you are screaming at the top of your long loud enough to jam GPS, you are being more than noisy enough for a missile to follow the signal back to the source.

Third, the airplane was not 'forced down'. If the story is true, what happened was they aborted their mission. That seems like a pretty legitimate thing to do if the mission isn't critical. I am sure they could have carried on if they wanted to, but they decided to play it safe. They were flying close to hostile territory doing a mission that will be fine if it waits a day or two longer. Hell, they might not even known they were being jammed until after the fact and were just concerned that their GPS equipment was malfunctioning. Delaying a signal flight for a couple of hours is hardly a stirring victory. If those plans had been sent to do something hostile, GPS jamming wouldn't have worked. The jammers would have been quickly destroyed or the plans could have navigated and hit their targets without GPS, or more likely, both would have happened. The jammer would have been destroyed and the plans on a mission would have merrily carried on without waiting.

The US military is designed to go toe to toe with Russia and China, who field unknown numbers of hackers, crackers and other cyberwarfare experts. Go ahead and assume that the idea of changing the default password on their servers has crossed their minds.

if you are dumb enough to turn on a GPS jammer powerful enough to knock out a plane's GPS navigation during a time of conflict, you pretty much deserve the missile that is going to fly up your arse a few minutes later. Jamming is done by blasting a very powerful signal out into the air. A very powerful signal is trivial to track.

Actually, a powerful signal can be very difficult to triangulate, a 'very strong' signal would mean you have a very wide area where it could be coming from, not so trivial compared

I doubt it was near the border, more likely the U.S. plane completely disregarded the border and the U.S. government is lying about the whole thing.

When I made my military service in the Swedish air force in the early 1990's, several NATO spy planes passed over Swedish air space every week. Since there was no point in letting U.S.A. know that the Swedish defence system was able to see them, Sweden only complained about a very small number of the really slow or clumsy ones and then got some lame excuse that they had navigated wrong. Since U.S./NATO had many moles within the Swedish Armed Forces, they likely knew that Sweden knew anyway, they also likely knew that we could have taken down at least 1/3 of them while they were still inside Swedish air space, even if the passovers usually took less then a second. The planes was way to fast, well camoflaged and agile to be civilian aircraft’s, there were never any doubt that they were military or that most of them came from NATO (unless NATO allowed foreign spy planes to land on their military bases and air craft carriers). [ Biting my lip to not expose anything that could still be a Swedish military secret ]

There were occasional Russian spy planes passing over Sweden too, but at the time I made my military service, the Warsaw pact and the Soviet Union had just ceased to exist and the Russian government was more focused on what happened inside their country then spying on foreign nations. At least at that time, Russian spy technology was also still more advanced then the NATO one, so they could likely get the same information as the NATO spy planes without flying into foreign territory.

P.S. Most of the NATO spy planes likely didn't spy on Sweden, but on Russia and other former Warsaw Pact countries, most of the spy planes passing over Sweden flew into such territories or turned just before they reached their borders, Sweden just happened to be in between. NATO/U.S. had easy and cheap direct access to that kind of Swedish military secrets through all their moles within the Swedish armed forces, no need to send expensive air planes.

With the exceptions of help in the case of a natural disaster (as if the North Koreans would accept that), we can safely assume that any large-scale military action by the US in NK would either start with covert operations or areal bombardment.

To answer the question in the summary: yes, of course, the US military would be able to perform operations in NK.

It appears to be a comint prop-job.:) The fact that it got hit by what apparently was a UWB signal is interesting, given the Air Force's interest in that area of emissions the last decade or so. Let's not get too hasty in crowing North Korea "electronic warfare kings" just yet, though.:)